John C. Loper

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The gene coding for the Candida tropicalis NADPH-cytochrome P-450 oxidoreductase (CPR, NADPH: ferricytochrome oxidoreductase, EC was isolated by immunoscreening of a C. tropicalis lambda gt11 expression library and colony hybridization of a C. tropicalis genomic library. The C. tropicalis CPR gene produces a 2.35-kilobase mRNA transcript, levels of(More)
Phanerochaete chrysosporium, the model white rot fungus, uses P450 monooxygenation for oxidation of xenobiotic chemicals. To characterize its P450 systems, we have isolated two tandemly linked full-length P450 monooxygenase genes, pc-1 (2510bp) and pc-2 (2503bp). cDNA sequence and splice site analysis showed multiple small putative introns (35-82bp), 17 in(More)
The major cytochrome P450 in the yeast Saccharomyces cerevisiae, lanosterol 14 alpha-demethylase (ERG11), catalyzes an essential reaction in the biosynthesis of ergosterol, the predominant sterol of yeast. Protein levels of this cytochrome P450 are known to be affected by carbon source, oxygen, and heme, as well as the growth state of the culture. We have(More)
Proteins from eight eukaryotic families in the cytochrome P-450 superfamily share one region of sequence similarity. This region begins 275-310 amino acids from the amino terminus of each P-450, continues for approximately 170 residues, and ends 35-50 amino acids before the carboxyl terminus. The region can be divided into four domains of sequence(More)
Properties of a population of carbenicillin- and gentamicin-resistant, tobramycin-susceptible Pseudomonas aeruginosa at Veteran's Administration Hospital, Cincinnati, Ohio, have been followed during a 16-month period. As originally described, the strains were isolated from patients with urinary tract colonizations and were predominantly Parke-Davis(More)
The halotolerant alkane-assimilating yeast Debaryomyces hansenii was examined for P450 alkane hydroxylase genes known to be required for alkane assimilation in Candida. Four distinct P450alk gene segments and an allelic segment were isolated using PCR based on degenerate primers derived from the CYP52 family of alkane-inducible P450 genes. A screen of a(More)
The white rot fungus Phanerochaete chrysosporium metabolizes a range of xenobiotics via P450 mono-oxygenation, particularly under peroxidase-suppressing culture conditions. Here we report the cloning and analysis of the gene from this fungus for the cytochrome P450 oxidoreductase (CPR) and its differentially terminated cDNAs. Using a PCR-based approach with(More)
The P450alk gene, which is inducible by the assimilation of alkane in Candida tropicalis, was sequenced and characterized. Structural features described in promoter and terminator regions of Saccharomyces yeast genes are present in the P450alk gene and some particular structures are discussed for their possible role in the inducibility of this gene.(More)
We have sequenced the structural gene and flanking regions for lanosterol 14 alpha-demethylase (14DM) from Saccharomyces cerevisiae. An open reading frame of 530 codons encodes a 60.7-kDa protein. When this gene is disrupted by integrative transformation, the resulting strain requires ergosterol and, as expected, grows only in the absence of oxygen. The(More)
Compounds that compete with folic acid (folic acid antagonists [FAAs]) become limited in their usefulness in the treatment of leukemia, malaria, and bacterial infections by the rapid development of resistance. Assays of the plasma levels of certain of these FAAs led to the observation, in about 25% of the determinations, that a higher density of growth of(More)